This invention relates to a folding screen useful in conjunction with transparent and translucent skylights, and roof panels of various types, all of which are designed to control the light and heat generated by the sun's rays, and are referred to generally as skylights. In particular, skylights transmit light in the range from about the near-infrared to about the near-ultraviolet regions, not all of which light is desirable all the time. The folding screen of U.S. Pat. No. 3,924,671, the disclosure of which is incoporated herein by reference as if fully set forth, is designed to control sunlight transmitted by a skylight. It was essential, for proper functioning of the screen, that adjacent hinges, each formed by interdigitation of longitudinal edges of the panels, be vertically displaced relative to one another, a principle of operation which is common to both the patented screen and our novel screen.
To maintain the relatively vertically displaced relationship of adjacent hinges, the patent provides a bi-level track on each side of the screen. In a first embodiment the bi-level track comprises a lower track and a vertical guiding lip; in a second embodiment the bi-level track comprises a lower track and an upper track. Roller means travel in the lower track; and on the upper track, washer or spacer means (in the first embodiment), and roller means (in the second embodiment), maintain the relative vertical displacement of the adjacent hinges. In relatively wide folding screens, particularly those having a width greater than about 6 feet, the patented screen required interdigitation of panels having a length corresponding to the width of the screen, and contiguous panels of such length have a tendency to bind when interdigitated, due to their weight which is supported only at the tracks at the ends of the panels. Also, notching a panel is not only technically difficult, but weakens the panel making it less rigid and thus increasing its tendency to bind. As a consequence, patented folding screens were made with arcuate panels which, because of their geometry, had the dual disadvantages of covering less area than planar panels for a given mass of extruded resin, and of occupying far too much space when the panels are stacked, (the screen's collapsed position). Moreover, rollers on the lower track are expensive to install, require too much maintenance to be attractive, and adherence to the principle of preventing the screen to assume a planar position necessitated a bi-level track, irrespective of the particular embodiment chosen, all of which further increased the expense of manufacturing the screen. It was the necessity of solving these problems economically which spurred the invention of the novel folding screen which now permits the use of planar panels, obviates the use of bi-level tracks, rollers and spacer means, and the necessity of interdigitating contiguous panels; and at the same time, simplifies its operation.
Various folding panel structures have been designed for diverse purposes such as garage doors, hatch covers, awnings, cabinet closures, and the like. Of necessity, each particular folding panel structure is directed to the specific purpose for which it is designed, is essentially complete taken alone, and neither requires nor suggests that any other reference's structure be utilized to supply additional features to help execute the function of that particular folding panel structure. This is to be expected since folding panel structures are used in a host of diverse industries wholly unrelated to one and another. A light-permeable radiation screen in particular, must be designed subject to myriad considerations so that it is as functional as it is compatible with a specific roof structure.
The folding screens of the prior art, as might be expected, disclose numerous ways to cope with the particular problems posed by: (a) the type and geometrical disposition of the opening to be screened, for example, a garage, swimming pool, shower stall, window, furniture cabinet, etc.; (b) the size and shape of the screen; (c) the guide means for the screen and how and where these guide means may be located; (d) the drive means to be employed to open and close the screen, whether manual or not; (e) the exposure of the screen to the elements; and, not less important than any of the foregoing among still other considerations, (f) the cost of manufacturing the folding screen.
A Venetian blind has been used as a skylight screen as disclosed in U.S. Pat. No. 3,265,117, to Lorentzen et al, with a ladder assembly or tapes, and strut-like members which act as mechanical ties. A retractable or foldable roof for covering a swimming pool is designed in U.S. Pat. No. 3,333,621 to Elder, to function as a load bearing structure which seals out wind, snow and rain. Though Elder does not define the problem, he has circumvented a problem similar to the one faced by applicants, namely, binding of the panels when the screen is to be collapsed after it is opened. Elder uses grooved wheels mounted coaxially with the hinge axis of an upper hinge, and grooved wheels mounted coaxially with the hinge axis of a lower hinge, which wheels are translatable along widely separate paths. The result is that the screen never assumes an undulating near-planar position.
A folding cover for a cabinet is disclosed in U.S. Pat. No. 3,570,579 to Matsushima. The cover is pendently supported and includes plural panels hingedly connected with a hinge of special design, which hinge permits adjacent panels to rotate through an angle of 120.degree.. This rotation permits the panels to be folded in a stacked relationship, either vertically or horizontally, by virtue of the weight of the panels which commence to fold only after their weight is unsupported. The fitting slots in the specially designed hinge limits the rotation of a panel in only one direction, and this design is essential for the folding cover to assume a planar configuration when it is opened, this planar configuration being so essential that even the visible portions of the hinges are designed to preserve the planar appearance of the cover. However, the arcuate fitting slots cause binding of relatively long panels, that is, panels which are at least 3 feet long, such as are used for a folding screen for a skylight.